The SR 99 TBM — Bertha — reached her stopping point in the access pit on Tuesday night, March 3, clearing the way for Seattle Tunnel Partners to begin a disassembly process that will likely take weeks.
Bertha moved forward a total of 57 ft between Feb. 17, when mining resumed, and March 3. Along the way the TBM built nine permanent concrete tunnel rings. With Bertha now in position, crews have begun the challenging task of taking apart the world’s largest tunneling machine. They will move through a number of methodical steps as they prepare to lift four pieces weighing up to 2,000 tons to the surface for repairs. Among other things, they must disconnect hundreds of hoses and cables, remove motors and weld lift points to the machine’s exterior.
When disassembly is complete, a massive crane will move into position above the pit. Several pieces of the machine will be removed before the cutterhead is lifted out of the pit. For more reports and link to videos, visit www.alaskanwayviaduct.org